Glass formation, crystallization and luminescent properties of Pr³ ⁺-doped oxyfluoride barium borosilicate glasses

The glass-forming behavior, phase separation, crystallization, thermophysical properties, and Pr³ ⁺ luminescence of nominal compositions in the SiO₂–B₂O₃–(0.8BaO/0.2BaF₂) pseudo-ternary system were investigated. The aim was to establish the experimentally observed glass-forming region and immiscibility behavior, characterize composition-dependent crystallization and thermophysical properties, and evaluate the optical response of a representative Pr³ ⁺-activated boroaluminosilicate glass. The glasses were prepared by conventional melt-quenching at 1100–1550 °C and characterized by differential thermal analysis/differential scanning calorimetry (DTA/DSC), high-temperature dilatometry, X-ray diffraction (XRD), optical transmission spectroscopy, and photoluminescence under 473 nm excitation. The BaO/BaF₂ ratio was fixed at 80:20 and treated as a pseudo-component, while the reported compositions represent nominal batch compositions. The system exhibits a relatively wide experimentally determined glass-forming region and stable and metastable liquid–liquid phase separation, with the immiscibility boundaries shifted toward lower modifier concentrations relative to the fluorine-free oxide analog. The glasses show glass-transition temperatures of 560–605 °C, softening temperatures of 670–710 °C, crystallization-onset temperatures of 1060–1150 °C, and linear thermal expansion coefficients of (72–115) × 10⁻⁷ K⁻¹ . Crystallization behavior strongly depends on SiO₂ content and involves barium borate, borosilicate, and oxyfluoride-containing crystalline phases. Pr³ ⁺-doped glasses exhibit broad absorption bands and visible photoluminescence, with pronounced orange–red emission near 610 and 645 nm under 473 nm excitation. The results demonstrate that variations in the SiO₂/B₂O₃ balance within the fixed 0.8BaO/0.2BaF₂ pseudo-component framework provide effective compositional control over glass formation, liquid–liquid phase separation, crystallization, thermal behavior, and Pr³ ⁺ luminescence, highlighting the potential of these glasses for luminescent converters, photonic components, and related optoelectronic applications.